The killing fields: chimpanzees wage war for new territory

A group of chimpanzees in Uganda has been observed killing members of a …

While conquests and invasions form a major part of human history, it's now clear that we aren't the only species that murders each other for land. A short correspondence in Current Biology details the first conclusive evidence that chimpanzees can gain extra territory after killing members of a neighboring group.

The Ngogo group of chimpanzees in Uganda's Kibale National Park has been watched for 10 years, and is larger than many other well-studied groups. Beginning in 1999, several members of the Ngogo group were repeatedly observed leaving their territory and embarking on "boundary patrols" in an area inhabited by another group of chimpanzees. During these patrols, members remained quiet, traveled in a single file line, and refrained from foraging or socializing. Between 1999 and 2008, the Ngogo chimpanzees attacked and killed 13 chimpanzees (four adult males and nine younger animals) in the neighboring group's territory during boundary patrols.

By 2009, the Ngoro chimpanzees began to regularly feed, rest, and socialize in the northeastern area, where the patrols had previously taken place. Meanwhile, the neighboring group of chimpanzees was no longer observed in the vicinity. Over the next five months, the Ngoro chimpanzees spent 32.3 percent of their time in this newly-acquired area, using it exactly as they did the rest of their territory. The range expansion increased the size of their territory by 22.3 percent.

Previously, two groups of chimpanzees in Tanzania have been suspected of similar conquests, but there was not enough evidence to identify a causal link between intergroup aggression and territory expansion. The authors provide two hypotheses for this lethal behavior: the chimpanzees probably sought out new land either to procure more mates or to increase their food supply. More evidence is required to tease out the particular forces that drive this type of range expansion.

The authors are careful to warn that these observations cannot be used to shed light on many forms of human human violence. Human war is an incredibly complex phenomenon stemming from many sources, and may not have as strong an evolutionary basis as lethal aggression among other primates.

Kate Shaw Yoshida
Kate is a science writer for Ars Technica. She recently earned a dual Ph.D. in Zoology and Ecology, Evolutionary Biology and Behavior from Michigan State University, studying the social behavior of wild spotted hyenas. Emailkate.shaw@arstechnica.com//Twitter@KateYoshida

"The authors are careful to warn that these observations cannot be used to shed light on many forms of human human violence. Human war is an incredibly complex phenomenon stemming from many sources, and may not have as strong an evolutionary basis as lethal aggression among other primates."

Yeah yeah, humans are so very special and unique. No, we are just like our closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

We're actually very close to both chimpanzees and bonobos. When researchers gave a group of chimps a big cardboard box, they fought over who got to control it. When they gave a box to bonobos, they climbed inside and had sex.

No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

We're actually very close to both chimpanzees and bonobos. When researchers gave a group of chimps a big cardboard box, they fought over who got to control it. When they gave a box to bonobos, they climbed inside and had sex.

Why couldn't we be more like bonobos, and less like chimpanzees?!?

Did the chimpanzees sit outside and call the bonobos "lazy, long-haired, commie hippies"?

No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

We're actually very close to both chimpanzees and bonobos. When researchers gave a group of chimps a big cardboard box, they fought over who got to control it. When they gave a box to bonobos, they climbed inside and had sex.

Why couldn't we be more like bonobos, and less like chimpanzees?!?

Don't you wish it was as simple as a cardboard box. Buy something from Amazon and get laid. Not a bad bonus.

Seriously, I was going to quote the same passage. It is nice to put a disclaimer, that human war is different. The key is that humans have historically used violence as a means to achieving a goal, like territory expansion. Just ask the native americans.

Bah, seems like more and more I'm seeing the same papers covered by multiple blogs. I guess that's a good indication that they're surprising or interesting, but the deja vu is messing with my head! I had to skim the NI archives to see if this was already covered or if I was just crazy. Luckily I remembered that Ed Yong wrote about it.

It is nice to put a disclaimer, that human war is different. The key is that humans have historically used violence as a means to achieving a goal, like territory expansion. Just ask the native americans.

Not that I condone war/violence for territory expansion, but at least it's rationalized as a fight over resources. When we have wars over ideology, it's a true sign that we do not live up to our own label of 'civilized'. That makes us worse than other species.

(Add to that our unchecked population growth and we have set a course for serious conflicts in the future. Then we will have resource issues and the intractable ideological differences to contend with. I can't wait.)

No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

We're actually very close to both chimpanzees and bonobos. When researchers gave a group of chimps a big cardboard box, they fought over who got to control it. When they gave a box to bonobos, they climbed inside and had sex.

Why couldn't we be more like bonobos, and less like chimpanzees?!?

Some of us are. It would be nice if the rest would get on board and stop acting like dicks.

"The authors are careful to warn that these observations cannot be used to shed light on many forms of human human violence. Human war is an incredibly complex phenomenon stemming from many sources, and may not have as strong an evolutionary basis as lethal aggression among other primates."

Yeah yeah, humans are so very special and unique. No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

I think you meant to say "just like our closest living relatives". I'll leave any further discussions on that point to others.

We're actually very close to both chimpanzees and bonobos. When researchers gave a group of chimps a big cardboard box, they fought over who got to control it. When they gave a box to bonobos, they climbed inside and had sex.

Well, maybe humans are a bit of both. They fight over control of the box, then have sex in it

Not that I condone war/violence for territory expansion, but at least it's rationalized as a fight over resources. When we have wars over ideology, it's a true sign that we do not live up to our own label of 'civilized'. That makes us worse than other species.

When kids don't share, they hit each other, and adults tell them to stop. When adults don't share, they kill each other and no one tells them to stop.

Not that I condone war/violence for territory expansion, but at least it's rationalized as a fight over resources. When we have wars over ideology, it's a true sign that we do not live up to our own label of 'civilized'. That makes us worse than other species.

When kids don't share, they hit each other, and adults tell them to stop. When adults don't share, they kill each other and no one tells them to stop.

I would go so far as to question if there has been a pure ware over ideology, or if control of resources was the hidden agenda, using religious views as the excuse. For some reason it seems to have become more socially acceptable to kill over ideology than resource control.

No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

We're actually very close to both chimpanzees and bonobos. When researchers gave a group of chimps a big cardboard box, they fought over who got to control it. When they gave a box to bonobos, they climbed inside and had sex.

Why couldn't we be more like bonobos, and less like chimpanzees?!?

Don't you wish it was as simple as a cardboard box. Buy something from Amazon and get laid. Not a bad bonus.

Seriously, I was going to quote the same passage. It is nice to put a disclaimer, that human war is different. The key is that humans have historically used violence as a means to achieving a goal, like territory expansion. Just ask the native americans.

I think you left off part of the last sentence. Pretty sure what you meant was this: "Just ask the Native Americans, who consistently waged war against and took slaves from other tribes in order to assert their dominances and expand their territory." I'm sure you weren't just espousing that silly idea that The White Man(tm) came in and introduced the native populations to that sort of behavior, whereas previously they had lived in peace and harmony with absolutely no concept of tribal territory.

Not that I condone war/violence for territory expansion, but at least it's rationalized as a fight over resources. When we have wars over ideology, it's a true sign that we do not live up to our own label of 'civilized'. That makes us worse than other species.

Wars are not typically fought over ideology. Those are just the motivations those in power use to get public acceptance for them.

Human war is an incredibly simple phenomenon excused by many complex rationalizations, and made more destructive by many complex inventions. We differ from the other apes in our superior tool-making skills and (possibly) in our more-evolved ability to use abstract language that masks our monkey- / lizard-brain motivations.

"The authors are careful to warn that these observations cannot be used to shed light on many forms of human human violence. Human war is an incredibly complex phenomenon stemming from many sources, and may not have as strong an evolutionary basis as lethal aggression among other primates."

Yeah yeah, humans are so very special and unique. No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

I think you meant to say "just like our closest living relatives". I'll leave any further discussions on that point to others.

Human war is an incredibly simple phenomenon excused by many complex rationalizations, and made more destructive by many complex inventions. We differ from the other apes in our superior tool-making skills and (possibly) in our more-evolved ability to use abstract language that masks our monkey- / lizard-brain motivations.

Human war is an incredibly simple phenomenon excused by many complex rationalizations, and made more destructive by many complex inventions. We differ from the other apes in our superior tool-making skills and (possibly) in our more-evolved ability to use abstract language that masks our monkey- / lizard-brain motivations.

The authors make the distinction to discourage people from jumping to this conclusion. It's not that this conclusion is wrong, but that it is unproven, and not generally accepted by certain groups. The distinction is purely political to make sure their research doesn't step on the ideological toes of those who fund their research.

Is this really a new discovery? Haven’t we been observing Meerkats and other mammals displaying this behavior for decades? Am I missing what makes the observation in this article unique or new?

I wanted to ask the same question. Meerkat Mansion was a good view into territorial wars. Hell, they kill *their own fellows*, not just the ones they want to take land from - and all because they had the temerity to get pregnant.

I would go so far as to question if there has been a pure ware over ideology, or if control of resources was the hidden agenda, using religious views as the excuse. For some reason it seems to have become more socially acceptable to kill over ideology than resource control.

And what about indigenous peoples, living in a state of harmony with the Eden-like environment? Well, they never did. On this continent, the newly arrived people who crossed the land bridge almost immediately set about wiping out hundreds of species of large animals, and they did this several thousand years before the white man showed up, to accelerate the process. And what was the condition of life? Loving, peaceful, harmonious? Hardly: the early peoples of the New World lived in a state of constant warfare. Generations of hatred, tribal hatreds, constant battles. The warlike tribes of this continent are famous: the Comanche, Sioux, Apache, Mohawk, Aztecs, Toltec, Incas. Some of them practiced infanticide, and human sacrifice. And those tribes that were not fiercely warlike were exterminated, or learned to build their villages high in the cliffs to attain some measure of safety.

How about the human condition in the rest of the world? The Maori of New Zealand committed massacres regularly. The dyaks of Borneo were headhunters. The Polynesians, living in an environment as close to paradise as one can imagine, fought constantly, and created a society so hideously restrictive that you could lose your life if you stepped in the footprint of a chief. It was the Polynesians who gave us the very concept of taboo, as well as the word itself. The noble savage is a fantasy, and it was never true. That anyone still believes it, 200 years after Rousseau, shows the tenacity of religious myths, their ability to hang on in the face of centuries of factual contradiction.

There was even an academic movement, during the latter 20th century, that claimed that cannibalism was a white man's invention to demonize the indigenous peoples. (Only academics could fight such a battle.) It was some thirty years before professors finally agreed that yes, cannibalism does indeed occur among human beings. Meanwhile, all during this time New Guinea highlanders in the 20th century continued to eat the brains of their enemies until they were finally made to understand that they risked kuru, a fatal neurological disease, when they did so.

More recently still the gentle Tasaday of the Philippines turned out to be a publicity stunt, a nonexistent tribe. And African pygmies have one of the highest murder rates on the planet.

In short, the romantic view of the natural world as a blissful Eden is only held by people who have no actual experience of nature. People who live in nature are not romantic about it at all. They may hold spiritual beliefs about the world around them, they may have a sense of the unity of nature or the aliveness of all things, but they still kill the animals and uproot the plants in order to eat, to live. If they don't, they will die.

I've always loved his take on mythological "noble savage". Every creature has always waged war and killed it's competitors. It irks me when people start talking about us wiping out the (original) native Americans. As Quietstorm said above, they were here busily waging violent war against each other.

The authors [state] that these observations cannot be used to shed light on ... human [behaviour]

Indeed not. The only thing that can "shed light" on human behaviour is human behaviour.

The reference to "complex[ity]" and the phrase "evolutionary basis" are also interesting.

The word "basis" indicates a standing back by the writers from the notion that biological theory can adequately explain ourselves. It's interesting that "complexity" is explicitly pointed to, as well.

Philosophers have long pointed to problems with the assumption that natural selection can adequately explain the lives of more complex beings and particularly of humans. (That it can is, however, orthodoxy among evolutionary biologists -- and, actually, always has been, although they tended not to say so too loudly until (relatively speaking) recently.) But it's refreshing to find biologists who are also awake.

Vide Mary Midgely and, in particular, the brilliant Australian philosopher David Stove:

"The authors are careful to warn that these observations cannot be used to shed light on many forms of human human violence. Human war is an incredibly complex phenomenon stemming from many sources, and may not have as strong an evolutionary basis as lethal aggression among other primates."

Yeah yeah, humans are so very special and unique. No, we are just like our closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

Yes, so true. This explains humanity's creation of art, literature, science, religion, music, entertainment, etc. Oh, wait.....Detailing the ways we are similar is good science. Ignoring the enormous ways in which we differ is bad science.

No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

We're actually very close to both chimpanzees and bonobos. When researchers gave a group of chimps a big cardboard box, they fought over who got to control it. When they gave a box to bonobos, they climbed inside and had sex.

Why couldn't we be more like bonobos, and less like chimpanzees?!?

One of the truths of human existence is conflict has been one of the propelling forces that has advanced our species. It started with the humble origins of primitive man banding together to kill other species and protect himself from becoming food. It was an important component in the development on human civilization from tribe to chieftain to state level civilization. It has continued to mold the development of state level civilizations. It may get us killed, but bemoaning its existence is to condemn one of the major forces that have brought us so far.

No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

We're actually very close to both chimpanzees and bonobos. When researchers gave a group of chimps a big cardboard box, they fought over who got to control it. When they gave a box to bonobos, they climbed inside and had sex.

Why couldn't we be more like bonobos, and less like chimpanzees?!?

Some of us are. It would be nice if the rest would get on board and stop acting like dicks.

No, we are just like are closest living relatives, and guess what, at base we are animals very much driven by an instinctive will to survive and propagate our own genes.

We're actually very close to both chimpanzees and bonobos. When researchers gave a group of chimps a big cardboard box, they fought over who got to control it. When they gave a box to bonobos, they climbed inside and had sex.

Why couldn't we be more like bonobos, and less like chimpanzees?!?

One of the truths of human existence is conflict has been one of the propelling forces that has advanced our species. It started with the humble origins of primitive man banding together to kill other species and protect himself from becoming food. It was an important component in the development on human civilization from tribe to chieftain to state level civilization. It has continued to mold the development of state level civilizations. It may get us killed, but bemoaning its existence is to condemn one of the major forces that have brought us so far.

++

Best post here.

A lot of the technology that grows hippie weed and feeds hippies TV dinners have come from military developments.

I sometimes shudder to think what humankind would look like today without centuries of war. I know this sounds like a jarhead thing to say, but think about it. A lot of good has come from a lot of bad.

That Michael Chrichton quote needs to have some fact checking applied. It isn't completely known the absolute cause of the mega-fauna extinction of the Americas. It is most likely a combination of drastic climate change and human exploitation. And the New Guinea highlanders ate the brains of their loved ones. Women and children ate the brain as a sign of honour and respect for the recently deceased.